Client's husband can't email her since she changed her domain hosting

I recently revamped a friend's website, and moved it from her former hosting account at WebAmerica to my HostGator hosting account. Her primary email was me***ie@herwebsite.com, and of course, when we moved her site, it stopped working. Then I made her an identical email account through HostGator (still me***ie@herwebsite.com, and got her back up and running. Her email works fine; lots of people have emailed her since the change, including me.

Since the changeover, her husband cannot email her from his Mac. He can from his BlackBerry, no problem. On the Mac, he uses Apple Mail 2.936. I think I know what the issue is (90% sure, anyway), but can't see any good way to fix after looking through my own copy of Apple Mail (which I never use and have no experience with, btw-- I'm a Thunderbird gal).

The problem is this: the husband's primary (and, I believe, ONLY) email is l***y@hiswebsite.com. Before I moved the wife's site, hiswebsite.com and herwebsite.com were both hosted on WebAmerica. Instead of going out and checking the MX record for me***ie@herwebsite.com, Apple Mail appears to be saying, "Well, heck-- I know exactly where to find me***ie@herwebsite.com, right where it's always been!", resulting in the following bounce:

Hi. This is the qmail-send program at
my-hosting-server.com.
I'm afraid I wasn't able to deliver your message to
the following addresses.
This is a permanent error; I've given up. Sorry it
didn't work out.

<me***ie@my-hosting-server.com>:
This address no longer
accepts mail.

Note: Melanie's website is NOT my-hosting-server.com, which appears to be the email server for WebAmerica.

First, I suggested that the husband remove me***ie@herwebsite.com from his address book and previous recipients, in order to force Apple Mail to go out and find the correct delivery route for the address. This appears to have made no difference. A smart tech guy from HostGator then suggested that he go into the Accounts section and delete the my-hosting-server.com account, but to my mind, that will also delete his own primary email address (***ry@hiswebsite.com, hosted through WebAmerica), which would be, to put it mildly, bad. Especially since he is not a computer person, and blames HostGator (and by extension, me) for his current email woes.

Erm, I think that's about it for background info. Basically, the question is: how does one force Apple Mail to check and update the MX record of an email address that it thinks is local (same server as the sending email address- my-hosting-server.com), but which has, in reality, moved?

Hi. This is the qmail-send program at
my-hosting-server.com.
I'm afraid I wasn't able to deliver your message to
the following addresses.
This is a permanent error; I've given up. Sorry it
didn't work out.

You can also delete Mail's cache in ~library\\caches\\com.apple.mail
and ~library\\caches\\mail

And not sure how long ago you made this change but it can take a few hours to filter through the internet. And then double check that hisdomain.com DNS servers know about herdomain.com MX record. Just because others can email if his Domain Registrar hasn't received the updated MX then... poof

You can also delete Mail's cache in ~library\\caches\\com.apple.mail
and ~library\\caches\\mail

And not sure how long ago you made this change but it can take a few hours to filter through the internet. And then double check that hisdomain.com DNS servers know about herdomain.com MX record. Just because others can email if his Domain Registrar hasn't received the updated MX then... poof

Thank you. This is very, very useful. I'm going to call his domain registrar today and have a word with them before I try to talk a non-computer person three states away through flushing his cache. (Still- the website transfer was done two weeks ago, so you'd think that the rest of the internet would have gotten the message by now). \

At the 'find recipient' stage, it appears to be bouncing back from his SMTP server.

It will work from his Blackberry as that will use a different SMTP server as will most people trying to contact the woman. The fact they had domains with the same provider will mean that the hosting provider probably has some internal configuration about where the mail should go.

A quick solution would be to get him to change his SMTP server address. You can use any SMTP server really, even a hostgator one.

Marvin's way would probly work but I don't recommend it. Its not "best practice" because receiving SMTP servers often perform Reverse DNS lookups, SPF lookups, DomainKey lookups, and may bounce the message back. You want a solution that is guaranteed to work